The MLG of an aircraft is usually housed in cavities in the ventral fairing, and in the wing equipped with doors that are opened when the MLG is going to be deployed and that are closed after the MLG has been retracted into said cavities.
When the MLG is deployed in emergency conditions, these cavities cause disturbances on the downstream air flow that may cause problems to aircraft equipment located behind them such as a RAT.
A RAT is a small turbine connected to a hydraulic pump or electrical generator which is installed in an aircraft and used as an emergency power source. A RAT system generates power from the airstream taking advantage of the aircraft speed. Modern aircraft use the RAT only in emergency cases—i.e. loss of primary and auxiliary power sources—to supply their vital systems (i.e. flight controls, linked hydraulics and flight-critical instrumentation).
The prior art has not paid much attention to the effects of said disturbances due, probably, to the fact that they only occur during the deployment/retraction of the MLG. On the other hand, it is not expected a priori that the disturbances caused by cavities in the external surface of an aircraft may severely affect aircraft equipment placed behind them.